The cellular heterogeneity of the CNS has severely limited our ability to examine either its constituent cell classses or the manner in which these classes interact to elicit normal brain function. Available evidence indicates that like neurons, both astroglia and oligodendroglia possess membrane receptors which respond to chemical messages. It is also apparent that each of these three classes may contain a number of pharmacologically-distinct cell populations.. The primary objective of this study will be to isolate and characterize discreet populations of brain cells. Initial studies will employ present laboratory techniques to prepare virtually pure separate primary cultures of neurons, astroglia and oligodendroglia from neonatal rat cerebral cortical tissue. Laboratory results indicate that cultures of astroglia and oligodendroglia are better than 98% homogeneous. Purified neuronal cultures have not been fully characterized yet but appear to be at least 90% homogeneous. Preliminary experiments will expand the cellular characterization of each culture and optimize the growth conditions necessary for each cell class. Spleen cells from mice immunized with these purified cell clases will be fused with myeloma cells to obtain cell hybrids secreting cell specfic monoclonal antibody. Antibody which selectively binds to only a fraction of the cells present within a class will be used to divide the cell class into distinct cell populations. The pharmacology of each of the immunologically distinct cell population will be examined by characterizing the factors regulating cyclic AMP accumulation.